Add swimm verify to Travis build

.travis.yml

@@ -96,6 +96,13 @@ script:
 - cd $TRAVIS_BUILD_DIR/docs
 - hugo --verbose --environment staging
 
+# verify swimm
+- cd $TRAVIS_BUILD_DIR
+- wget https://firebasestorage.googleapis.com/v0/b/swimmio.appspot.com/o/Release%2Fv018%2Fswimm-0.1.8-linux-executable\?alt\=media\&token\=e59c0a18-577f-4b77-bb3b-91b22c3d8b2a -O swimm
+- chmod +x ./swimm
+- ./swimm --version
+- ./swimm verify
+
 after_success:
   # Upload code coverage results to codecov.io, see https://github.com/codecov/codecov-bash for more information
   - bash <(curl -s https://codecov.io/bash)